#lang sicp
;; 2.53
(define (memq item se)
  (cond ((null? se) #F)
        ((eq? item (car se)) se)
        (else
         (memq item (cdr se)))))



;; 2.54
(define (equal? a b)
  (if (and (pair? a) (pair? b))
      (and (equal? (car a) (car b))
           (equal? (cdr a) (cdr b)))
      (eq? a b)))

;; 2.55
'abc
(quote abc)
''abc
(quote (quote abc))
(car ''abc)
(car (quote (quote abc)))